Dual-AAV delivering split prime editor system for in vivo genome editing

Prime editor (PE), a new genome editing tool, can generate all 12 possible base-to-base conversions, insertion, and deletion of short fragment DNA. PE has the potential to correct the majority of known human genetic disease-related mutations. Adeno-associated viruses (AAVs), the safe vector widely used in clinics, are not capable of delivering PE (∼6.3 kb) in a single vector because of the limited loading capacity (∼4.8 kb). To accommodate the loading capacity of AAVs, we constructed four split-PE (split-PE994, split-PE1005, split-PE1024, and split-PE1032) using Rma intein (Rhodothermus marinus). With the use of a GFP-mutated reporter system, PE reconstituting activities were screened, and two efficient split-PEs (split-PE1005 and split-PE1024) were identified. We then demonstrated that split-PEs delivered by dual-AAV1, especially split-PE1024, could mediate base transversion and insertion at four endogenous sites in human cells. To test the performance of split-PE in vivo, split-PE1024 was then delivered into the adult mouse retina by dual-AAV8. We demonstrated successful editing of Dnmt1 in adult mouse retina. Our study provides a new method to deliver PE to adult tissue, paving the way for in vivo gene-editing therapy using PE.